Cylinder grinding tool



w. F. MITCHELL 7 2,400,430

CYLINDER GRINDING TOOL I I May 14, 1946.

Filed 001;. 14', 1943 v INVENTOR.

- vfi- I Patented May 14, 1946 UNIT ED STATES PATENT OFFICE Q I 7 2,406,430- g CYLINhER GRINDING root Wallace F. Mitchell; Chicago, 111., assignor to Au-- tomotive MaintenancegMachinery 00., Chicago, Ill.,a. corporation of Illinois Applicationoctober 14, 1943, Serial-N; 506,210

18- Claims. (01. 51-1843) My invention relates generally to tools adapted for the grinding of the bores of engine, pump and other cylinders either in factory production work or in the reconditioning of worn cylinders, andit has to do particularly" with tools of theforegoing character embodying expansible and contractible abrading stones.

One of the objects of my invention is to provide an improved tool of the foregoing character which is of simple and rugged construction, is economical to manufacture, is adapted to' grind cylinders and the like to accurate dimensions quickly and with a minimum of power and effort, and which is adapted to perform its cylinder grinding functions in a more efficient manner than prior devices.

Another object is to provide a cylinder grinding tool adapted to provide a fast and smooth cutting action during the grinding operation without chatter and with a minimum of grinding stone wear.

A further object is to provide av tool of the foregoing character which is provided with means for automatically expanding the abrading stones against the cylinder wallin such a manner as to. maintain theabrading su-rfacesof such stones in a clean, non-clogged and 'non lazed. condition during. the grinding operation, so that'such abrading stones are adaptedto exert their maximum cutting or grinding; action during the grinding operation. I

Still another object is to: provide acylinder grinding tool having. expansible abrading stones, the arrangement being such that alsubstantially uniform and highly effective grinding. action is accomplished even though thegrit and grades of the stones employed may vary. Heretofore it has been necessary, in an attempt toarrive at an efiicient grinding action for any; particular tool," to carefully. select the abrading stones so as to-substantially match'them in-respect-to the grit andgradethereof. According tomy invention, the abrading stones-may be engaged with the cylinder Wallundervariable pressures, which pressures in any particular. tool aresufficient :to accommodate a wide. range. of stone grading. For example, softstcnes, which requirea low pressure in the grinding operation may be emplcyed by use of the.desired. rinding pressure as determined by the expanding. adjustment of the tool; or harder stones which require. agreater rinding pressure may be. employedby adjusting th sameexpanding' means'to' ap ly a greater grindingpressure; all of which. may." be accomplished I withoutaffectingtthe expansion range of the expanding means of the tool. Furthermore, in accordance with my invention,- the foregoing adjustment features are accomplished with a fast and smooth cutting operation which is devoid of chatter and which is carried out with a minimum of stone wear. I

A further object is to provideabrasive exp'anding means for a cylinder grinding tool which is of compressible form having one part with a low deflection and a high frequency characteristic and another part with a highdeflection and-a low frequency characteristic. 1

A more specific object is to" provide abrasive expanding means for: a' tool of the foregoing character which takes the form' of a pair of springs of substantially equal loadc'arrying capacity, one of which has a high rate'of' vibration and the other of which has a low rate of vibration, the springs being so arranged that the high rate spring is compressed and held compressed during the grinding operation by the low rate spring; whereby the-high rate spring is effective for transmitting cutting vibrations to the cutting stones throughout the range of any'particular tool adjustment as determined bythe extent of compression of the low rate spring.

An additional object is' t'oprovide spring expanding means of the foregoing character wherein the springs are so related as to insure at all times during the grinding operation the high frequency action of the high frequency spring to maintain the grinding surface of the abrading stones in a clean, full-cutting condition and in such" rhythm as to prevent chatter.

Still'another object is to provide an improved means for automatically limiting the extent of automatic expansion of the tool during any particular grinding operation;

parent as'this'description progresses'and'by reference to the drawing wherein.-

Figure 1 is an elevational' view, partially in section, of one form of cylinder grindin tool embodying my invention;

Fig. 2 is' a section taken substantially on line 2+2 of Fig. 1';

Fig. 3 isv a bottom plan view partially in section; and

. Fig. 4' is a fragmentary elevationalviewillustrating the means by which the tool-is manually adjusted. 7

Referring to the drawing-, the tool embodying my invention is well adapted for the grindin of acylinder I0. Such-tool is of theso-called rigid cage-frame type comprising a pair of end plates i8, such stones being secured in, place withinthe channel of the abrasive carrier head by clamp blocks IS. The particular tool shown in the drawing employs four abrasive carrier's 4, two of which carriers support abrading stones I8, and

the other two support felt guide members 20- which are employed for a purpose well under stood in this art.

The tool shown is of the expansible, contractible type, expansion of the carriers |4 being accomplished by an adjustable floating cone unit.

This cone unit comprises a threaded stem 2| which extends along the axis of the tool and is of suificient length to project its lower end through an opening 22 in the-lower end plate |2 and through and beyond a universal drive head 23 formed exteriorly on the upper end plate I The stem 2| supports a pair of unidirectional cone members 24, 25, the conical surfaces of which engage complementally shaped surfaces formed along theinner edges of the carrier bodies M. The cones 24, 25 are provided with peripheral notches 21 that receive a post 25 carried by the end plates II and I2 whereby the cones are permitted to shift axially of the tool without rotation thereof relative to the tool body. With this arrangement, rotation of the stem 2| relative to the cones 24, 25 causes such cones to shift axiv ally along the carrier surfaces |4 to expand and contract the latter. The carriers are retained yieldably in engagement with the cones 24 and 25 by garterlike springs 28' and 29 seated in notches formed in the outer edge of the end por- I tions of the carriers adjacent the carrier supporting grooves and I6. These springs 28, 29 are also efiective to contract the carriers l4 upon contraction adjustment of the stem 2| and cones 24, 25.

The stem 2| is also free for axial shift move-V r ment under the control of spring means. This shift movement of the stem 2| also bodily shifts the cones 24, 25 to expand the carriers 4 and stones l8 against the cylinder wall. To this end, I provide an enlarged axial opening 30 in the universal drive head 23 through which axially passes the upper end of the stem 2|. The spring means for moving the cone unit is located in the opening 30 and takes the form of a comparatively thin, washer-type spring 3|, cupped or dished as indicated in Fig. 1. The edge of the spring 3| in the form shown seats upon the bottom of the opening 30, which bottom surface is'preferably hardened to prevent the edge of the spring from digging in and causing the same to become paralyzed and inoperative. If desired, a hardened washer (not shown) may be inserted under the spring to accomplish the same purpose. The spring 3| is of predetermined load carrying capacity, has a small deflection characteristic and has a high rate of vibration. Upon the spring 3| there is mounted a coil spring 32 having substantially the same load carrying capacity as the spring 3|, but a high deflection characteristic and a comparatively low rate of vibration. The

spring 3| is seated upon the bottom of the opening 30 and both springs surround the upper end of the stem 2|, being confined as a unit between the bottom of the opening 30 and a depending skirt-like portion 33 of a knurled adjusting knob 34. The skirt-like portion 33 of the adjusting knob is secured to the stem 2| by a pin 35 or like means. V

In the useof the foregoing structure, the tool is first contracted by rotating the adjusting nut 34 and stem 2| in a left-hand or counterclockwise direction. In this operation the stem 2! rotates without axial shift movement while the cones 24,

. 25.'are shifted alongthe stem in carrier contracting directionl The tool is then placed in the cylinder |0 to b'e-ground, after which the adjusting nut 34 is,turned in a right-hand or clockwise direction to expand the tool to an extent to bring theabrasive stones l8 and felts 20 into firm engagement with the cylinder wall. In this operation, the cones 24, 25 only are shifted axially by movement along the stem 2|. However, in finally adjusting the tool to compress the springs 3|, 32

forautomatic 'tool expanding and grinding operation, a different action takes place. In further rotation of the adjusting knob 34 and stem 2|, after the stones have engaged the cylinder wall, the cones 24, 25 remain stationary While the stem 2| shifts axially downward to compress the springs 3|, 32. The extent of rotation of the knob '34 and the stem 2| depends upon the amount of material to be removed from the cylinder wall. After this final adjustment is made, the spring unit 3|, 32 constantly urges the stem 2| upward tending to move the cones 24, 25 in the same direction to automatically expand the carriers I4. As the tool is rotated and material is removed from the cylinder wall the tool is springs 3|,32. Thusly, the lower end of the stem and the stop block 36 are utilized as adjustment limiting means, and-the extent to which the tool may be expanded under the control of spring expanding means is determined by the extent of rotation of the stem 2| after the stones engage the cylinder wall and the distance that the stop block 36 moves downwardly away from the bottom end plate l2. 7

It will be recognized by those skilled in the art that one may determine with a fair degree of accuracy the amount of material that will be removed'from the cylinder wall with any particular adjustment. For example, one may readily determine the extent to which the adjusting knob 34 need be turned in a particular tool for removal of a certain amount of material for the cylinder wall,and to facilitate accuracy in useof thetool I have provided an indicator by which the operator may determine the extent to which the tool has been adjusted and in turn the amount of material that may be removed from the cylinder wall. To this end I have provided immediately beneath the adjusting knob 34 a"rotatab1e'sleeve 31 having at its upper edge a somewhat enlarged peripheral knurled bead 38 'whichmay be radilygrasped for turning thesame. Y The sleeve '31 is rotatably confined-between a lock ring 39 on the adjusting knob skirt'3 3 and the. underside of the adjusting knobfa disk-like spring 40 being disposed between the'knob 34 and the sleeve 31 toupermit relative rotation of the sleeve and the knob when so desired but tootherwise cause the two to. rotate. together. The sleeve 31 is provided with aicalibrated scale which registerswith a suitable indicating mark 23 exteriorly visible on the universal drive head 23'. In this use of this structure, after the abrading stones I:8 have been set up initially against the cylinder wall and before final adjustment is made to compressjthesprings. 3|, 32, the sleeve 31 is rotated to bring its. zero mark in line with the indicating mark 23* on the head: 23. v knob. 34 is thenv rotated as above explained, carrying the sleeve with it, the distance that the zero'mark of the sleevemoves away from the indicating mark on the head 23 indicating the extent to. which the tool has been adjusted for the. grinding operation and indicating the extent .to. which material will be removed from the 7 cylinder wall before the adjustment limiting :block;3iiv becomes effective to stop furtheradjustment of. thetool.

a -The tool. may bedriven by any suitable power means such as an electric drill or the like. 'To adapt it for driving, I preferably employ a universal coupling sleeve '4Ladaptedlto operably engage pins 42. on. the universal drive head 23, which'sleeve is pivotally carried bya yoke-like member43. to which is rigidly secured a drivin spindle 44. This .spindle may be connected directly. to thepower means which may be such as to merely rotate the tool or both rotate and reciprocate the same.

The construction and operation of my invention will, I believe, be understood from the foregoing description. Thorough demonstration has shown that in. the use of a tool embodying my invention. the grinding operation is carried out smoothly and without chatter; it is carried out much more rapidly than in any ,known prior tool, and abrading stone wearis reduced to the practical minimum. IIhaVe found by demonstration, operatin the tool inthe manner of prior tools, that I am able to remove .005" of material from the cylinder wall in approximately. one. minute, or more than twice as fast as prior tools. Demonstration has further shown that this amount of material may, with my invention, be removed without any appreciablewearonthe grinding stones and throughout the operation, the tool does its work with a smooth-non-chatter action. From. my analyses of the tool inoperation andotherwise, I believe that theseoutstanding results, which havelon been sought but heretofore unachieved, are. due in part at least to the novel spring expanding meansemployed in carrying out my invention.

A thin washer-type of spring, such as, the spring 31-, when under compression, furnishes fast, or high-speed vibrations, that is,- a natural period of,- vibration of high frequency, which keep the. abrading stones in substantially continuous. contact with the cylinder wall. This high speed vibration, however, is such that the surface of theabrading stone through its rapid vibrating. contact. with they cylinder wall is con.- stantly; kept, substantially clean at: all. times so that the" full; intended: cutting. effect: of; the

The adjusting r vibration the abrading stone surface is constantlyunloaded and the stones do not become clogged or glazed. 3

A fiat washer-type spring-has a total movement from a free lengthcondition to compressed length condition'of' only a few thousandths of an inch sothat it wouldbe necessary, in the use or; such "spring without other compensating means, toirequently adjust the tool when remo'ving any appreciable amount of material from the cylinder wall. Such adjustment would requirefrequent stoppage of the tool, slowing up the operation considerably. In carrying out I my invention,'I eliminate the foregoing disadvantage of the high rate spring by the use of the slow or low speed (low rate of vibration) spring such as the coil spring 32. The coil type of spring 32, as is well known, furnishes slow or low-speed vibrations, that is, a natural period of vibration of low frequency, and, if used alone, would tend to cause the abradingstones to bounce, so to speak, against the cylinder wall so that chattering would take place. This would also tend to cause the stones to break down and wear out quickly, in addition to slowing up the grinding operation due to the outof-contact period-of the abrading stones with the cylinder wall; However, when this, low rate spring (like 32) is used with a high rate spring (like 31), all ofthe foregoing objectionable conditions disappear and: new" and novel results are obtained. In the claims, I havereferred to the washer-type spring as a high frequency spring and the coil spring as a low frequency spring. r

In carrying out my invention I have coordinated the low-speed and high-speed springs in such a way as to secure the. advantages of both without the defects of either. These springs are preferably of the same load capacity When the coil spring 32 is compressed it likewise places the disc sprin under compression and it main iting means above described. Consequently, in

the useof-my tool, I gain the cutting or grinding action, the stone cleaning feature and the nonchatter feature, of the high frequency spring, such as the spring 3|, while at the same time gaining in the use of a spring like spring 32, a wide range of adjustment without stoppage of the tool during the grinding operation.

I claim: l. A cylinder grinding tool comprising a body, abrasive carriers mounted in said body for expanding and contracting movements, abrasive elementscarried by said carriers, and means for expanding said carriers which includes a pair of coacting springs, one having a high frequency and the otherhaving a low frequency, and means disposed between said springs and said carriers for compressing said springs and adapted to be shifted-by said springs when compressed to expand'said carriers and hold said abrad-ing elementsin abrading contact with the cylinder wall.

,- 2. A cylinder grinding tool comprising a body,

abrasive carriers'mountedin said body for expanding and contacting movements, and means for expanding said carriers which includes a-pair of'coacting springs having different frequencies, and means disposed between said springs and said carriers for compressing said springs and upon which said springs when compressed act to expand said carriers. a

3. A cylinder grinding tool comprising a body, abrasive carriers mounted in said body for expanding and contracting movements, and means for expanding said carriers which includes a pair of springs of substantially equal load carrying capacity so arranged that one spring acts upon the other, said one spring having a lower frequency than the other spring, and means disposed between said springs and said carriers and adjustable to place said springs under compression and adapted to be moved by said springs when compressed to expand said carriers.

4. A cylinder grinding tool comprising a body, abrasive carriers mounted in said body for expanding and contracting movements, and means for expanding said carriers which includes a pair of springs of substantially equal load carrying capacity, one being capable of small deflection only for a given load and the other being capable of substantially greater deflection for said given load, the arrangement being such that one of said springs acts upon the other, and means disposed between said springs and carriers and adjustable to place said springs under compression and movable under the infiuenceof said springs when compressed to expand said carriers.

5. A cylinder grinding tool comprising a body, abrasive carriers mounted in said body for expanding and contracting movements, abrasive elements carried by said carriers, and means for expanding said carriers which includes a pair of springs of substantially equal load carrying capacity, one of said springs having small deflection ability with a high frequency and the other having greater deflection ability with a low frequency, a member operably engaged with said carriers and shiftable to expand the latter, said member being adjustable to'compress said springs, the arrangement being such that said high frequency spring acts upon saidrmember through said low frequency spring to shift said member to expand said carriers and to hold the abrasive elements thereof in grinding contact with the cylinder wall to be ground. 7

6. A cylinder grinding tool comprising a body, abrasive carriers mounted in said body for expanding and contracting movements-and means for expanding said carriers which includes a shiftable device acting on said carriers to expand the latter, and means for automatically shifting said device in expanding direction which includes a compressible unit having one portion adapted to operate with a high frequency of vibration and a coacting part adapted to operate with a low frequency of vibration.

7. A cylinder grinding tool having a body, abrasive carriers mounted in said body for expansion and contraction movements, an expanding unit which includes a shiftable member, expanding elements on said shiftable member adapted to engage and expand said carriers as said member shifts, and compressible means cooperating with said shiftable member to shift the same and expand said carriers as the grinding operation progress, said compressible means having one part capable of small deflection for a given load and another coacting part capable of greater deflection for said given load, said two parts having different frequencies of vibration.

8. A cylinder grinding tool having a body, abrasive carriers mounted in said body for expansion and contraction movements, an expanding unit which includes a shiftable member, expanding elements on said shiftable member adapted to engage and expand said carriers as said member shifts, and compressible means cooperating with said shiftable member to shift the same and expand said carriers as the grinding operation progresses, said compressible means having one .part with a high frequency of vibration and another. part with a low frequency of vibration.

9. A cylinder grinding tool having a body,

abrasive carriers mounted in said body for expansion and contraction movements, an expanding :unit which includes a shiftable member, expanding elements on said shiftable member adapted to engage and expand said carriers as said member shifts, and compressible means adapted to be compressed by adjustment of said shiftable member and acting on said shiftable member to shift the same, and expand said carriers as the grinding operation progresses, said compressible means including a pair of springs, one capable of small deflection and a high frequency of vibration and the other capable of greater deflection and a lower frequency of vibration, said springs acting one directly upon the other and having substantially the same load carrying capacity.

l0. A cylinder grinding tool having a body, abrasive carriers mounted in said body for expansion and contraction movements, an expanding unit which includes a shiftable member, expanding elements on said shiftable member adapted to engage and expand said carriers as said member shifts, and compressible means cooperating with said shiftable member to shift the same and expand said carriers as the grinding operation progresses, said compressible means including a pair of springs, one of which is a disk type spring having small deflection and a high frequency and the other of which is a coil spring having considerably greater deflection and a low frequency.

11. A cylinder grinding tool comprising a body, abrasive carriers mounted in said body for expansion and contraction movements, abrasive elements carried by said carriers and adapted to engage the cylinder wall to be ground, carrier expanding means including a stem member mounted for axial shift movement in said body, expanding elements on said stem member adapted to engage said carriers and expand the same as said stem member is shifted, and compressible meansadapted to be compressed by said stem member for shifting said stem member and having one part with low deflection ability and another coacting part with high deflection ability.

12. A cylinder grinding tool comprising a body, abrasive carriers mounted in said body for expansion and contraction movements, abrasive elements carried by said carriers and adapted to engage the cylinder wall to be ground, carrier expanding means including a stem member mounted for axial shift movement in said body, expanding elements on said stem member adapted to engage said carriers and expand the same as said stem member is shifted, and compressible means adapted to be compressed by said stem member for shifting said stem member in tool expanding direction and having one part 2,4o0,43o I automatically expanding said carriers which in- -witha high frequency of vibration and another cludes a rotatable threaded member shiftable coacting part withalowafredrency of vibration.

13. A cylinder grinding tool comprismgabodyo axially of said body, nonrotatable expanding eleabrasive carriers mounted in said body for exa plurality of abrasive carriers mounted in said body for expansion movement, abrasive elements carried by said carriers and adapted to engage the cylinder wall to be ground, and means for extent of permitted expansion of said carriers ments carriedbysaid member and engaging said the extent of shift movement of said member to compress said spring means and in turn the pansion and contraction movements, abrasive 5 carriers to expand thedatierastheymreM elements carried by said carriers and adapted axially, and means for shifting said member to engage the cylinder wall to be ground, carrier which includes a pair of springs confined beexpanding means including a stem member tween said member and said body, one of said mounted for axial shift movement in said body, springs having a low deflection and high freexpanding elements on said stem member adquency characteristic and the other having a apted to engage said carriers and expand the high deflection and' a low frequency charactersame as said stem member is shifted, and comistio, said springs acting directly on each other pressible means for shifting said stem member with one spring acting directly on said member. and having one part with a low deflection but 17. A cylinder grinding tool comprising a body, high frequency of vibration characteristic and 1 abrasive carriers mounted in said body for exanother part with a high deflection but low frepansion movement, abrasive elements carried by quency of vibration characteristic, one of said said carriers and adapted to engage the cylinder parts acting on the other which in turn acts on wall to be ground, carrier expanding means said stem member to shift the latter. mounted in said body including a member shift- 14. A cylinder grinding tool comprising a body, able axially to expand said carriers, a stop on one a plurality of abrasive carriers mounted in said end of said member adapted to engage said body body for expansion movement, abrasive elements and limit shift movement of said member in carried by said carriers and adapted to engage the carrier expanding direction, compressible spring cylinder wall to be ground, and means for automeans for automatically shifting said member matically expanding said carriers which includes in carrier expanding direction, said member bea member axially shiftable in said body, expandingshiftable in a direction opposite its carrier ing elements carried by said member and eh- I expandingshift movement to compress said comgaging said carriers to expand the latter as said pressible means, said latter shift movement of member is shifted axially, and means for shifting said member moving said stop away from said said member which includes a compressible unit body a predetermined distance to permit a preof substantially uniform load carrying capacity determined shift movement of said'member in throughout while having one part constructed carrier expanding direction to effect a predeter to have a high frequency of vibration and another mined carrier expansion. part constructed to have a low frequency of vibra- 18. A cylinder grinding tool comprisingv a body, tion. I abrasive carriers mounted in said body-for ex- 15. A cylinder grinding tool comprising a body, pansion movement, abrasive elements carried by a plurality of abrasive carriers mounted in said said carriers and adapted to engage the cylinder body for expansion movement, abrasive elements wall to be ground, carrier expanding means carried by said carriers and adapted to engage mounted in said body including a member shiftthe cylinder wall to be ground, and means for 40 able axially to expand said carriers, a stop on one automatically expanding said carriers which inendof said member adapted to engage said body cludes a rotatable threaded member shiftable and limit shift movement of said member in I axially of said body, nonrotatable expanding elecarrier expanding direction, compressible spring ments carried by said member and engaging said means for automatically shifting said member carriers to expand the latter as they are shifted in carrier expanding direction, said member be axially, and means for shifting said member ing shiftable in a direction opposite its carrier which includes a compressible unit confined beexpanding shift movement to compress said comtween said member and said body, said unit bepressible means, said latter shift movement of ing in part constructed for low deflection anda said membermoving said step away from said high frequency of vibration and in part for high body a predetermined distance to permit a predeflection and a low frequency of vibration, said determined shift movement of said member in unit being compressed by rotation of said memcarrier expanding direction to effect a predeterber with said abrasive elements engaged with the mined carrier expansion, and calibrated indicator cylinder wall to be ground. V means carried by said member for determining 16. A cylinder grinding tool comprising a body,

WALLACE F. MITCHELL. I 

